As a technique capable of measuring a visual line with high accuracy in a non-contact manner, a corneal reflection method has been known. This method uses reflected light on an eyeball, and therefore the accuracy is largely affected by the individual difference of an eyeball shape. Consequently, a measured visual line is corrected using an individual error.
PTL 1 discloses a gaze point detection device including a plurality of stereo cameras that obtain a facial image of an object person, a light source disposed outside an opening of the stereo camera, a control circuit, and an image processing device. The image processing device calculates an angle of a visual line of the object person by using a function based on the facial images, calculates a direction of the visual line while correcting the function such that directions of visual lines calculated corresponding to the plurality of stereo cameras are close to each other, and detects a gaze point of the object person on a display screen.